Cyclone separator



June 16, 1936. KEENAN 2,044,614

CYCLONE SEPARATOR Original Filed Aug. 30, 1933 O W 6m ATTORNEYS PatentedJune 16, 1936 one SATS CYCLONE SEPARATOR Original application August 30,1933, Serial No.

Divided and this application January 16, 1936, Serial No. 59,334

1 Claim.

This invention relates to improvements in devices for separatingparticles of denser substance from liquid or gas streams by swirling thestream and its particles in a free or constrained vortex. 5 I shallrefer to all such devices, whether for completely separating particlesand stream or merely for concentrating the particles within a portion ofthe stream, as cyclone separators. ent application is a division of myapplication Serial No. 687,401, filed August 30, 1933 now Patent2,033,470 issued Mar. 10, 1936.

The common type of cyclone separator consists of the following parts: acylinder into which the particle-laden stream is introduced through aduct of round or approximately square crosssection, the outside wall ofthe duct being tangent to the cylinder wall at entrance; a conicalchamber below the cylinder for collecting or leading oiT the separatedmaterial; a central outlet pipe, attached to the top of the cylinder andprojecting down some distance into it, leading directly to theatmosphere or to a duct.

There are, of course, many variations on this common type of design. Insome cases the inside wall of the incoming stream, instead of theoutside wall, is made tangent to the cylinder. This arrangement usuallyinvolves a departure from the usual circular cross-section of thecylinder toward a spiral cross-section. In some cases there is no outletpipe projecting down into the cylinder. Sometimes a number of cylindersof various diameters are placed one below the other in the order ofdescending size and connected by truncated conical pieces. In somedesigns guide vanes are arranged within the cylinder. My invention isapplicable to all of these types.

In any vortex or swirl in a fluid stream which completely fills thevortex chamber, (that is, it is not bounded at the top by a. liquidsurface) there is a pressure gradient, the pressure decreasing towardthe center of the vortex. This pressure gradient provides the radiallyinward accelerations to the stream which are necessary to the swirlingmotion. If, as in the usual cyclone separator, the stream leaves thecylinder or separating chamber through a central hole at the top andpasses directly to the atmosphere or to a duct then the minimum drop instatic pressure across the most perfect collector of this type would bethe pressure gradient integrated along a line passing through the vortexcenter between the inlet opening and the rim of the outlet hole. Thepressure drop along the stream path in a vortex results in an increasein the kinetic energy of the stream which, except for The presfrictionefiects, is an essentially reversible process; that is, the kineticenergy could, presumably, be reduced again to the original or entrancemagnitude with a rise in pressure equivalent (except for friction) tothe drop experienced in the separating vortex.

My invention provides means for recovering a large part of the pressuredrop through a separating chamber by reducing the velocity of the streamafter it leaves the separating cylinder in a properly designed chamberor passage and includes a diffusing passage arranged for substantiallyunidirectional flow connected tangentially to the central discharge pipeof a cyclone separator. The fluid stream is led out of the centraloutlet pipe of the separating chamber tangentially and in the directionof rotation into a gradually diverging passage the outlet area of whichis approximately the same as the inlet area of the separating chamber ifdischarging directly to the atmosphere, or is the same as thecrosssection area of the duct into which it leads. The cross-sectionarea of this diffusing passage at inlet generally should be smaller thanthe inlet area of the separating chamber because the velocity of thestream is higher at this smaller distance from the vortex center. Thisdevice is essentially different from the ordinary tangential outletheretofore used by some manufacturers in that it uses the kinetic energyof the stream issuing from the vortex to raise the static pressure inthe diffuser exit as well as to supply the velocity head in the exitduct. The tangential outlet method used heretofore results in almost nopressure rise through velocity reduction because the area at theseparator exit is equal to the inlet area and is consequently too largefor the higher velocity stream. The main stream of fluid in such casefills onlypart .of the crosssection area, the remaind 'upied by eddieswhich dissipate kinetic energy and reduce the possibility of diffusion.

The process of increasing the pressure along the path of a fluid streamby reducing its velocity I shall hereafter refer to as difiusion, andthe passage or chamber in which the process is carried out I shall calla diffuser, a diffusing passage, or a diffusing chamber. A diffuser isessentially a reversed nozzle since in a nozzle the stream increases invelocity and decreases in pressure in the direction of flow while in adiffuser the stream decreases in velocity and'increases in pressure inthe direction of flow.

The utility of my device consists in the reduction in powerconsumption-in the fan or compressor which provides the pressurediflerential for overcoming the various frictional resistances in thepath 01' the stream. It is obvious that any device which reduces thepressure drop in any part of the flow path will reduce the power inputto the Ian almost in direct proportion for the same rate of fluid flow.

In the accompanying drawing:

Fig. 1 is a vertical sectional view of a cyclone separator embodying myinvention; and

Fig. 2 is a transverse section on line 2-2 of Fig. 1. K

The separator shown in the drawing comprises vertical cylinder I inwhich the denser particles are separated from the fluid stream whichenters through approach pipe 2, lower conical hopper 3 for collecting orleading oil? the denser separated material and covered central dischargepipe 4 which projects some distance above the top oi.- the separator andthrough which the stream passes on its, way to diffusing passage 5.Difiuser 5 is attached tangentially to outlet pipe I, leading off in thedirection of motion of the rotating stream in the outlet pipe at thatpoint. The inlet cross-section area 6 of diffuser 5 should be less thanthe separator inlet area 2 because of the higher velocity existing at 6.Between inlet 6 and outlet section I the diflusing passage graduallyincreases in area until the area of the dis-" charge duct 1 is reached,If the diffuser discharges directly to the atmosphere its exit area maybe made as large as is economical; the larger it is. the smaller will bethe pressure drop across the device. v

The invention claimed is: The combination with a cyclone separator having a cylindrical separating chamber, a tangential inlet passagetherefor, and a central axial discharge pipe, of a tangential dischargepassage for said discharge pipe, said discharge passage having an inletarea smaller than that of said inlet passage and gradually increasing incrosssectional area in the direction of air flow to its 20 terminus.

JOSEPH H. KEENAN.

